Countermovement Jump Recovery in Professional Soccer Players Using an Inertial Sensor.

Purpose: To assess the utility of an inertial sensor for assessing recovery in professional soccer players.

Methods: In a randomized, crossover design, 11 professional soccer players wore shorts fitted with phase change material (PCM) cooling packs or uncooled packs (control) for 3 h after a 90-min match. Countermovement jump (CMJ) performance was assessed simultaneously with an inertial sensor and an optoelectric system: prematch and 12, 36, and 60 h postmatch. Inertial sensor metrics were flight height, jump height, low force, countermovement distance, force at low point, rate of eccentric force development, peak propulsive force, maximum power, and peak landing force. The only optoelectric metric was flight height. CMJ decrements and the effect of PCM cooling were assessed with repeated-measures analysis of variance. Jump heights were also compared between devices.

Results: For the inertial sensor data, there were decrements in CMJ height on the days after matches (88% [10%] of baseline at 36 h, P = .012, effect size = 1.2, for control condition) and accelerated recovery with PCM cooling (105% [15%] of baseline at 36 h, P = .018 vs control, effect size = 1.1). Flight heights were strongly correlated between devices (r = .905, P < .001), but inertial sensor values were 1.8 [1.8] cm lower (P = .008). Low force during countermovement was increased (P = .031) and landing force was decreased (P = .043) after matches, but neither was affected by the PCM cooling intervention. Other CMJ metrics were unchanged after matches.

Conclusions: This small portable inertial sensor provides a practical means of assessing recovery in soccer players.